1. Field
The present disclosure relates to a system for supplying vaporized natural gas, and more particularly, to a system for reducing a heating value of vaporized natural gas which is supplied to a user.
2. Description of the Related Technology
In recent years, the use of natural gas has rapidly expanded throughout the world. Natural gas is transported long distances in a gaseous state through a gas pipe line over land or sea, or is transported in a liquid state to consumers by liquefied natural gas (LNG) carriers. LNG is obtained by cooling natural gas into a cryogenic state (about −163° C.) where the volume of the natural gas is reduced to about 1/600 that at standard temperature and pressure, which makes it eminently suitable for long distance marine transportation.
The LNG carrier is provided for shipping and discharging the LNG when carrying it to a land destination by sea. For this purpose, the LNG carrier includes an LNG storage tank (i.e. a so-called cargo tank) capable of withstanding the cryogenic state of the LNG. Typically, the LNG carrier unloads or discharges the LNG from the LNG storage tank at a destination in the liquefied state, and the discharged LNG is gasified by LNG regasification equipment installed at the destination and is then supplied to natural gas consumers through the gas pipe line.
The land-based LNG regasification equipment is economically advantageous in the case where the equipment is installed in such a place where natural gas markets are actively and stably established to satisfy demand for natural gas. However, the land-based LNG regasification equipment is economically disadvantageous in the case where the equipment is installed in such a place where a market for natural gas is seasonal, short-term or periodic, since installation and maintenance of the LNG regasification equipment is relatively expensive.
In particular, if the LNG regasification equipment is destroyed by natural disasters or the like, even though the LNG carrier arrives at the destination to discharge the LNG, it is impossible to gasify the LNG. Therefore, there is a limit in transportation of the natural gas through the LNG carrier.
Accordingly, there has been developed a marine LNG regasification system wherein LNG regasification equipment is installed in the LNG carrier or a marine structure to gasify the LNG at sea and supply natural gas obtained by the regasification to the land. Examples of the marine structure with the LNG regasification equipment include an LNG RV (regasification vessel), an LNG FSRU (floating storage and regasification unit), etc.
Some examples of processing vaporized LNG are disclosed in U.S. Pat. No. 2,952,984, No. 3,282,060, No. 3,407,052, and the like. Further, one example of the method of adding nitrogen gas to natural gas is disclosed in U.S. Pat. No. 3,837,821.
The foregoing discussion is to provide general background information, and does not constitute of an admission of prior art.